We blogged on the beginning of this conversation last week, then got overwhelmed by our own Zygotes-turned-Big-Men come to visit. You might remember Andrew Sullivan putting out a call to readers regarding the mortality rate of zygotes, implying that this has something pertinent to do with the right to research on/kill said zygotes.

At The Corner, Ramesh Ponnuru, (whose book, The Party of Death: The Assault on the Sanctity of LIfe, is due out in April) responded, and exchanges ensued. At The Thing Is, Bradford Short has helpfully followed the conversation here and here. I believe the upshot is this: Sullivan wants to ascribe a very high mortality rate to young zygotes, but the counterargument, from Ramesh is that a large proportion of early miscarriages are, it seems, not properly-formed zygotes at all. They are anomolous – from a letter from a physician to both of them:

His point with regard to the nature of first trimester spontaneous abortions is more on point. One-third of the products of conception from spontaneous abortions are ‘blighted’ or anembryonic: no embryo is found in the gestational sac. In the other two-thirds of cases in which an embryo is found, approximately one-half are dysmorphic, abnormal, stunted and thus would not develop into a fetus. These unviable products likely result from chromosomal abnormalities or maternal exposure to teratogens.

The term ‘miscarriage’ does not technically pertain to fetal losses that supervene after a gestational age is reached when a child is viable outside the womb. This rate is low for structurally and chromosomally intact fetuses and is more dependent on maternal health and well-being and on the availability of physician oversight and modern obstetric care.

Your desire for the specific percentage of human zygotes that eventually emerge from the uterus as infants is a statistic that I believe cannot [be] empirically documented. However, it is clear that birth, the process of fertilization, uterine implantation, and embryonic and fetal development is fraught with peril, and can be colloquially, if not also theologically, be referred to as a ‘miracle.’ (emphases added by RP)

My fundamental point remains: I fail to see what a high mortality rate, if it exists, of very young human beings has to do with our rights to experiment on them or end their lives.